Some are, like the oft mentioned troika of WW Chan, Baroman, and A-Man Hing Cheong. They cut an individual pattern for each customer and if one is available, a full set of fittings is available. They will do most everything one requests, instead of sticking stubbornly to a certain house style. Chan's trips abroad, though, function more like MTM in that there are usually no subsequent fittings prior to the garment's completion.
Others are not bespoke, but MTM - they alter preexisting patterns instead of creating anew.